An outbreak of severe acute respiratory syndrome (SARS) emerged in Guangdong Province, People's Republic of China in November 2002. From China, SARS spread to 30 other countries and as of Aug. 7, 2003, this outbreak resulted in 8,422 reported cases, of which 918 were fatal. Through the coordinated efforts of laboratories around the world, a novel coronavirus, SARS-coronavirus (SARS-CoV), was identified as the causative agent of SARS (Drosten, et al., 2003, N. Engl. J. Med. 348:1967-1976; Fouchier, et al., 2003, Nature 423:240; Ksiazek, et al., 2003, N. Engl. J. Med. 348:1953-1966; Peiris, et al., 2003, Lancet 361:1319-1325; Poutanen, et al., 2003, N. Engl. J. Med. 348:1995-2005). This discovery was quickly followed by the publication of the complete genomic sequences of two SARS-CoV isolates and identification of specific subgenomic RNAs and proteins involved in replication (Marra, et al., 2003, Science 300:1399-1404; Rota, et al., 2003, Science 300:1394-1399; Thiel, et al., 2003, J. Gen. Virol. 84:2305-2315). Phylogenetic analysis of the SARS-CoV replicase gene demonstrated that despite a number of unique features, SARS-CoV is most closely related to group 2 coronaviruses, which include mouse hepatitis virus (MHV), bovine coronavirus (BCoV) and human coronavirus OC43 (HCoV-OC43) (Snijder, et al., 2003, J. Mol. Biol. 331:991-1004).
SARS-CoV has been detected using the Vero E6 cell line and fetal rhesus monkey kidney cells (the only cell lines reported to be susceptible to SARS-CoV). Susceptibility of these cells to SARS-CoV was based on observing a cytopathic effect (CPE) post inoculation with SARS-CoV. However, many coronaviruses cause persistent infections in cell cultures and some show little evidence of CPE. Thus, using CPE to identify entry of SARS-CoV or abortive replication is insensitive, misleading, and does not correctly identify virus entry and/or replication.
SARS-CoV has also been detected using virus titration techniques, RT-PCR specific to SARS-CoV genomic RNA, and immunofluorescence assay. However, these methods are laborious, and do not distinguish between entry and replication of the virus.
Thus, there remains a need for compositions and methods for detecting the presence of SARS-coronavirus, for screening anti-SARS coronavirus agents and vaccines. There is also a need for increasing the safety of cell cultures that are routinely used in laboratories and that may support infection by plus-strand RNA viruses, such as SARS-coronavirus.